Copper/zinc catalysts, particularly brass spelter catalysts have long been used commercially for the dehydrogenation of isopropyl alcohol to acetone. U.S. Pat. No. 3,558,716, issued Jan. 26, 1971, discloses a process for producing beta-branched aldehydes by means of dimerization/dehydrogenation utilizing a catalyst that can contain copper and zinc. However, in this reference the copper and zinc are in the form of the oxides rather than in the form of a metallic alloy such as brass.
In Japanese Pat. application 50-130780, published Oct. 16, 1975, saturated aliphatic primary and secondary alcohols are converted to their corresponding aldehydes and ketones utilizing as a catalyst brass rings. In this reference long catalyst life is obtained by operating at reduced pressures i.e., less than atmospheric. Exemplary pressures are given as 30-60 millimeters of mercury. The exemplification in this reference teaches a preconditioning of the catalyst with water prior to the reaction followed by the reaction with the appropriate alcohol in the presence of air. This preconditioning and carrying out of the reaction in air would be expected to convert the catalyst at least in part to oxides.
Applicant has found that the dehydrogenation of an alcohol with a brass catalyst in the presence of additional hydrogen can provide an enhanced catalyst life. The resultant product aldehydes are important chemical intermediates that can be converted to specific ethoxalates, carboxylic acids, amines, etc. which find use, for example, in the detergents area and in the oil additives area.